Cycling calorie burn varies hugely by weight, speed, terrain, and bike type. Here's the MET formula for accurate estimates and a reference table for every type of ride.
Cycling is one of the most calorie-efficient ways to exercise — it covers large distances with relatively little effort per kilometre, making calorie estimates highly dependent on effort level rather than distance alone.
The most accurate way to estimate cycling calorie burn uses the Metabolic Equivalent of Task (MET) — a measure of exercise intensity relative to sitting still.
Running burns roughly 2–2.5× as many calories per kilometre as cycling at equivalent effort, because running supports your full body weight against gravity. However, cycling allows you to cover much more distance in the same time, which narrows the gap per hour of exercise.
Most fitness watches and cycling computers overestimate cycling calorie burn by 15–30%. They often don't account for the fact that cycling is partially supported by the saddle, or that the aerodynamic position at speed reduces the energy cost compared to their estimates. Power meter data (measuring actual watts at the pedals) is the only truly accurate method — the MET formula is a reliable approximation for training planning.